Pre-insulated electrical connector and dies for applying same



March 15, 1966 R. F COBAUGH ETAL. 3,241,098

PRE -INSULATED ELECTRICAL commc'roa AND DIES FOR APPLYING SAME Original Filed July '7. 1961 X I A 3a INVENTORS Poem? F. CoBnucH DONHLD H. MPN eome T Dn-TER GT2.

United States Patent Office 3,241,098 Patented Mar. 15, 1966 3,241,098 PRE-INSULATED ELECTRICAL CONNECTOR AND DIES FOR APPLYING SAME Robert F. Eobaugh, Hershey, Donald H. May, Linglestown, and George T. Ritter, Jr., Harrisburg, Pa., as-

signors to AMP Incorporated, Harrisburg, Pa. Continuation of application Ser. No. 122,564, July 7, 1961.

This application Apr. 2. 1965, Ser. No. 445,163 2 Claims. (Cl. 339-213) This is a continuation of our prior application, Serial No. 122,564, filed July 7, l961, now abandoned, for Pro-Insulated Electrical Connector and Dies for Applying Same.

It is frequently desirable to insulate a crimped electrical connection with plastic having operating characteristics in the 500 range. One example of such a plastic is tetrafluoroethylene marketed under the trademark Teflon by Du Pont. One of the problems with these plastics is that they have a low compressive strength. As such, if it is attempted to crimp through the plastic to the metal underneath, the plastic may be squeezed out from under the crimping dies. This may cause dielectric failure of the insulating sleeve, rendering it worthless.

It is an object of this invention to provide a means of crimping metal through plastics, particularly useful for plastics having a low compressive strength. It is also an object of this invention to provide such a device to be used with ferrule-type connectors having a rib or beam at one end, whereby the required crimping pressure at that end of the insulation sleeve is reduced, thus precluding rupture of the plastic. Also, it is an object of this invention to prevent longitulinal flow at each end of the plastic sleeve whereby the tendency to rupture is reduced. It is a further object of this invention to confine the plastic in all directions and crimp uniformly throughout the entire sleeve of the plastic. It is also an object of this invention to crimp through plastic in the manner designed so as to eliminate sharp corners and thus prevent rupture of the plastic.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of the invention but are given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 illustrates a perspective view of a conductor and a connector made according to the principles of this invention;

FIGURE 2 illustrates an exploded view of the connector shown in FIGURE 1;

FIGURE 3 is a perspective view of the connector of FIGURE 1 crimped onto the conductor;

FIGURE 4 is a side view of a connector body without the insulating sleeve;

FIGURE 5 is a sectional view taken through plane 55 of FIGURE 7 and showing the connector and the conductor of FIGURE 1 in a pair of crimping dies;

FIGURE 6 is a perspective view of the dies; and

FIGURE 7 is a section taken through plane 77 of FIGURE 5.

As shown in FIGURE 2, the electrical connector comprises a ring tongue portion 10 which is formed as an integral part of a ferrule member 12. The conductorreceiving portion of the connector may be stamped out of copper and rolled up to form a ferrule. In the preferment, a first metal tubular member 14 surrounds the ferrule 12. A plastic insulating sleeve 16 surrounds the tubular member 14. The sleeve 16 may be of a high temperature plastic such as tetrafluoroethylene, known as Teflon, even though such material has low compressive strength. An outer metal ring 18 surrounds the free end of the plastic sleeve 16.

As shown in FIGURE 4, the end of the ferrule 12 having the ring tongue 10 emanating therefrom has a relatively high resistance to crimping pressure because of the rib or beam formed by the curvature of the metal where it blends from the ferrule into the tongue portion, as indicated by the letter B in FIGURE 4. A pair of recesses 20 and 22 (FIGURES 2 and 4) are formed in each side of the ferrule 12 in the vicinity of the curved portion B. This reduces the crimping pressure needed to be exerted on the ferrule at this point to crimp the ferrule to a conductor C without weakening the crimped connection.

With the connector assembled, a conductor C is inserted into the ferrule 12 with insulation D on the conductor abutting the open end of the ferrule 12 (see FIGURE 5). A pair of crimping dies are then brought to bear on the outer plastic sleeve 16 and metal sleeve 18 so that the pressure required to cold-forge or coin the ferrule to the conductor is transmitted through the plastic sleeve to the ferrule 14, thus crimping the ferrule onto the conductor C." The outer sleeve 18 is likewise crimped onto the insulation D of the connector. The insulation 16 is not ruptured or otherwise impaired.

FIGURES 6 and 7 illustrate a pair of dies suitable for crimping plastic having a low compressive strength. The set comprises an indenting die 30 and a nesting die 32. Each die has an insulation support crimping member 34) and 32 adapted to crimp the ferrule 18 on the outside of the connector.

The nesting die 32 is substantially U-shaped and of a length equal to the distance from the free end of the ferrule 12 to the inner end of the ferrule 18. The die surface 34 is slightly longer than the ferrule 12. The bottom surface of the die is arcuate and blends smoothly into a pair of parallel Walls to form a U-shaped crimping surface. The indenting die member 30 is of the same length as the die 32 and has an arcuate die crimping surface 36 which has the same radius as the arcuate surface 34. The sides of the indenter die 30 fit snugly within the sidewalls of the die nest 32. The crimping surfaces 34 and 36 have the same radius but reverse curvature so that the combination of the two dies forms an oval in cross-section (see FIGURE 7). The front surface of the lower die 32 contains a plate 38 which is shaped to permit the ring tongue 10 to extend therethrough but precludes lateral extrusion of the plastic sleeve 16. The opposite die 30 has a similar plate 40.

It has been discovered that plastic tends to shrink longitudinally when exposed to extreme temperature conditions. This might tend to expose the end of the ferrule 12 adjacent the ring tongue 10. To preclude this, recessed portions 42 and 44, in each of the dies 30, 32, respectively, permit the insulation 16 to bulge outwardly in this area. The recessed portion is properly radiused to prevent damage to the plastic. When the crimped connection is subjected to extreme heat, the shrinkage will be taken up in the bulge portion, whereby the metal ferrule 12 remains covered with insulation over its entire length.

The insulation support crimping dies 30', 32, resemble the dies 30, 32, with crimping surfaces 34, 36 corresponding to crimping surfaces 34, 36. However, in closed position (FIGURE 7), the distance between surfaces 34', 36' is slightly greater than between surfaces 34, 36. This accommodates the insulation support ferrule 18. As shown in FIGURE 5, all corners are smoothly radiused to prevent damage to the insulation. When the crimp ing pressure is applied to the connector, the sleeve or band 18 is crimped to the free end of theplastic sleeve 16. This serves to anchor the plastic in this direction against lateral flow. Continued crimping pressure causes the ferrule 12 to be crimped onto the conductor C. This is accomplished by transmission of crimping pressure through the plastic sleeve 16 to the ferrule 12. The flow plates 38 and 40 preclude extrusion of the plastic in a lateral direction. Furthermore, the notched-out portions 20 and 22 at the front end of the ferrule 12 reduce the required crimping pressure. It also insures that the ferrule :begins to collapse in the proper direction when crimping begins.

Crimping is continued until the ferrule 12 snugly is compacted onto the wire C, and the entire terminal is deformed into an oval-shaped, cross-sectional member (see FIGURE 7). The crimping dies are then released and the connector removed therefrom.

It is noted that the final result is a compact, crimped connection having high tensile strength and good operational characteristics at high temperature.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.

We claim:

1. A connector for crimping onto an electrical conductor comprising a metal ferrule, a connecting means comprising a substantially fiat metal portion integral with the ferrule, a pair of notches in the end of the ferrule,

each of said notches on opposed sides of the flat metal portion adjacent the connecting means, a plastic insulating sleeve surrounding said ferrule, of a plastic having low compressive strength and high temperature characteristics, whereby the ferrule may be crimped onto a conductor by pressure exerted through the plastic sleeve, Without rupturing or otherwise impairing the insulating characteristics of the plastic.

2. The device of claim 1 including a metal band surrounding the outside surface of the plastic sleeve at the end opposite from the fiat metal portion.

References Cited by the Examiner UNITED STATES PATENTS 2,371,469 3/1945 Rogolf 339276 2,406,079 8/1946 Krueger 339276 2,639,754 5/1953 Macy 72-411 2,693,216 11/1954 Kerchner et al. 72412 2,673,336 3/1954 Peters 339220 2,681,440 6/1954 Swengel 339276 X 2,700,144 1/1955 Flanagan 339217 2,789,277 4/1957 Schurnacher 339276 2,802,257 8/1957 Holtzapple 339223 X 2,807,792 9/1957 OKeefe et a1. 339276 2,809,364 10/1957 Mescan 339--276 2,815,497 12/1957 Redslob 339276 X 2,839,595 6/1958 Felts et al 339177 X 2,863,132 12/1958 Sowa 339276 X 3,067,489 12/1962 Hofi'man 339276 X 3,098,688 7/1963 Crimmins et al. 339223 

1. A CONNECTOR FOR CRIMPING ONTO AN ELECTRICAL CONDUCTOR COMPRISING A METAL FERRULE, A CONNECTING MEANS COMPRISING A SUBSTANTIALLY FLAT METAL PORTION INTEGRAL WITH THE FERRULE, A PAIR OF NOTCHES IN THE END OF THE FERRULE, EACH OF SAID NOTCHES ON OPPOSED SIDES OF THE FLATE METAL PORTION ADJACENT THE CONNECTING MEANS, A PLASTIC INSULATING SLEEVE SURROUNDING SAID FERRULE, OF A PLASTIC HAVING LOW COMPRESSIVE STRENGTH AND HIGH TEMPERATURE CHARACTERISTICS, WHEREBY THE FERRULE MAY BE CRIMPED ONTO A CONDUCTOR BY PRESSUE EXERTED THROUGH THE PLASTIC SLEEVE, WITHOUT RUPTURING OR OTHERWISE IMPAIRING THE INSULATING CHARACTERISTICS OF THE PLASTIC. 